Circuit controlling device



Juiy 26, '1938.v E, ZURCHER 2,125,695

CIRCUIT CONTROLLING DEVICE Filed NOV. 2,V 1934 A 2 She'S-Sheet l 5 Ihvemtor Ernest Zurcher,

by Www/59M His Attovmey jiy 26? ggg. E- ZURCHER 2,125,095

CIRCUIT CONTROLLING DEVICE Filed NOV. 2, 1934 2 SheecS-Shee' ,2

/40 ,lm/erwtor:

. Ernest Zurcher, byjqww Hrs Atto whey.

Patented July 26, 1938 PATENT OFFICE 2,125,095 CIRCUIT CONTROLLING DEVICE Ernest Zurcher, Schenectady, N. Y., assigner to General Electric il'ompany, a corporation of New York Application November 2, 11934, Serial No. 7511,168

23 Claims.

My invention relates to circuit controlling devices of the type used for the combined automatic and manual control of electrical apparatus, such for example, as refrigerators, and has for an object the provision of inexpensive, reliable means for operating a circuit controlling device to carry out a plurality of different' control functions.

While not limited thereto, my invention is parlo ticularly applicable to circuit controlling devices of the type shown in Letters Patent to Hutt Nos. 1,637,042 and 1,974,991, dated respectively July 26, 1927 andl September 25, 1934. The devices shown in the aforementioned patents are entirely l5 suitable for their intended purposes, but leave something to be desired in a control device occupyinga minimum amount of space and which at the same time carries out additional controlling functions in accordance with a variety of desired 20 operating conditions.

It is therefore a further object of my invention to provide a simple and inexpensive refrigerator control device for controlling the refrigerator motor so as to maintain a predetermined 25 average temperature in the refrigerator but which device can be adjusted at will to maintain within xed limits for a limited time a defrosting vtemperature above and a quick freezing temperature below the predetermined average tem- :20 perature.

Another object of my invention is to provide at all times compensated overload protection for the refrigerator motor of such character that the motor can be operated at full load, but not :i5 above full load, notwithstanding changes in the ambient temperature.

In carrying out my invention in one form thereof as applied to refrigerators, I provide a control device with an expansible bellows respon- 410 sive to the temperature of the refrigerator for moving against the bias of an adjustable temperature control spring a switch operating member. This temperature responsive movement of the switch operating member opens and closes 45 the refrigerator motor circuit to maintain a predetermined average temperature in the refrigerator. By adjusting the temperature control spring the average temperature can be raised or lowered within predetermined limits. In order a to raise the temperature of the refrigerator for a limited time a torsion spring under manual control opposes the movement of the switch member by the bellows. An oppositely acting torsion spring under manual control assists the 55 bellows to hold the switch closed so that a quick (Cl. 20d-81) freezing temperature is produced within the refrigerator. In case the switch is in the open circuit position at the time the control device is set for a quick freezing operation, provision is made to close the switch at once so that the lowering of the temperature in the refrigerator occurs in a minimum amount of time. A suitable compensating means is provided for the torsion springs so that the upper and lower limits of temperature in the refrigerator are always substantially the same irrespective of the adjustment of the temperature control spring. The manual control for initiating the defrosting and quick freezing operations is provided with automatic means for terminating the quick freeze l5 and defrost operations.

In a further aspect of my invention I provide an ambient temperature compensated overload device operated by a single opening spring to open the'circuit in response tol a predetermined 20 motor current. The opening spring also automatically resets the overload device. The control switch is trip-free at all times, that is to say, it cannot be maintained in the closed circuit position in case of an overload, irrespective of the positions of a manual operating means. The manual operating means itself forms a part of the overload device and -includes a pair of three surface camslwhich cooperate with each other and with the opening spring to provide quick opening of the contacts.

For a more complete understanding of my invention, reference should now be had to the drawings, wherein I- have shown in Fig. 1 a plan view of my invention applied to a refrigerator control switch with the cover removed; Fig. 2 is an exploded perspective View of the operating mechanism shown in Fig. l; Figs. 3, 4, and 5 are fractional plan views of the switch mechanism in different circuit controlling positions; Figs. 6 to 9 inclusive, are fractional plan views of the switch mechanism showing the parts in position for semi-automatic defrosting and semiautomatic quick freezing operations; FigsflOa to 10e, inclusive,fare enlarged detail views of the 45 three surface cams illustrating their position with respect to each other under various circuit oontrolling positions; Figs. 11 and l2 are plan views showing a portion of the overload mechanism in different positions, and Fig. 13 is an exploded 50 perspective view of that part of the circuit controlling device shown in Fig. 1 which is directly associated with the manual operating means.

Referring to the drawings, I have shown my invention in one form as applied to a refrigerl2 formed of insulating material. The refrigerator motor circuit is controlled by a pair of contacts M and I6, the contact lli being supported on a stationary conductor l'l secured in place by ineans of a brass conducting screw i8 which screw also serves to clamp a conductor i9 against an end wall 20 of the box I2. A screw 22 serves to clamp into electrical engagement with the con- ]ductor i9 a terminal 23.- The other side of the refrigerator motor control leading to the circuit controlling device l is by way of a terminal screw (not shown) mounted directly below the terminal screw 22 and electrically connected to a'conductor 2d.' The remainder of the circuit through the control device will be described more in detail in connection with the overload operation of the device. l

The movable contact i6 is mounted on a resilient conductor 26 preferably formed of bronze secured at one end 27 to a contact operating member 28. The contact operating member 28 is pivotally mounted upon a post Sii, the lower end of which is molded integrally with the side wall 32 of the box i2. The movable contact it is operated between open and closed circuit positions by means of a pivoted operating lever 3&3 and an over-center springr mechanism comprising an over-center spring 35 having one end t supported in a recess 31 provided in an extension 38 formed integrally with the Contact operating member 28. The other end i0 of the over-center spring is supported on the closed end lil of a U-shaped floating lever 42, the respective legs of the lever |52 being pivotally mounted in a U-shaped end i6 provided on the operating. lever 3Q. As shown ln Figs. 1 and 2 the force of the over-center spring is applied to the contact operating member in a clockwise direction to hold the movable contact |6 in the closed circuit position.

The operation of the movable contact i6 is determined as a function of the temperature of the refrigerator by means of a bulb (not shown) lled with a fluid having a low boiling point, such for example as methyl chloride or sulphur dioxide, the bulb being connected to a sylphon or expansible bellows 5U by means of a tube 52, which is soldered at 53 to one end 5d of the bellows Sli. A lock-washer 56 located between the bellows 5G and an end Wall 57 of the box l2 cooperates with a lock-nut 6G mounted on the portion lof the bellows extending through the end wallv 5l, to

fasten rigidly and securely the bellows in a fixed position. The opposite movable end 64 of the bellows bears against a centering washer 65 formed of insulated material, the centering washer serving the function of transmitting the pressure exerted by the bellows.5|l against the operating lever 36 and insulating the bellows from the control device.

In order to control the operation of the device I so as to provide for different average temperature in the refrigerator, a temperature control spring 68 is mounted to oppose the expansion of the bellows 50. Thus, one end 'i0 of the spring 68 bears against the operating lever 35 while the opposite end 'Il of the spring is mounted in a spring seat l2 having its inner portion i3 threaded to receive a screw lli. One end 'i5 of the screw lll extends through an end wall i6 of the box I0, the tendency for the outward movement of the screw 1d under the inuence of the spring 68 being opposed by means of a U-shaped locking member 'i8 having its respective legs 78a and- 18h nesting on opposite sides of a collar formed inator control device i0 mounted in a molded box tegrally. with the screw lll. The compression of the temperature control spring S8 is varied by rotating a temperature control knob 82 secured on the end i of the screw lii.y The spring 68 and the bellows 5U together form a flexible means for moving the pivoted operating lever 34 between open and closed circuit positions.

As shown in Figs. 1 and 2, the contacts l@ and i6 are in the closed circuit position with the refrigerator control circuit energized. The refrigerator motor is therefore in operation. As the temperature of the refrigerator is decreased by the refrigerating apparatus, it will be understood that the pressure of the bellows 5@ is correspondingly decreased solthat the temperature control spring 68 moves the operatinglever 36 about its pivot 86 in a clockwise direction, as viewed in Figs. 1 and 2. As the end M of the lever 312 moves towards the end 36 of the over-center spring 35, energy is stored in the spring so that the moment the .pivoted end of the U-shaped oating lever passes beyond the end 3E of the spring, the total energy of the spring quickly operates the floating lever i2 from its position against a stop t@ to a position against a stop Qi. The line of action of the spring is thereby shifted to the opposite side of the pivot 3G to operate the member 28 in a counter-clockwise direction. The result, of course, is that the movable contact I6 is operated to the open circuit position with a snap action.

Since the movement of the operating lever Sii depends upon the diierence between the pressures exerted upon it by the temperature control spring 68 andl the bellows 5|?, it will be obvious that the temperature setting of the device can be varied by changing the compression of the spring 68. For example, by rotating the knob in a counter-clockwise direction as viewed in Figs. 1 and 2 the spring seat 12 is moved in a direction to compress the spring 68. As the springv pressure is increased the temperature required in the refrigerator for the operation of the switch is correspondingly increased. Only a limited adjustment of the temperature control spring 63 is ordinarily provided so that the upper and lower temperature limits of normal operation are fixed.

In addition to the normal operation of the device between open and closed circuit positions, I provide for both manual and overload operation of the device to the open circuit position. For the sake of simplicity-of explanation, a portion of the mechanism for accomplishing these operations will now be described in detail.

The manual and overload separation of the contacts is effected by movement of an extension ll (Fig. 2) formed integrally with the contact' operating member 28. The extension is provided with a U-shaped end ||2, one leg H3 of which is operatively associated with one face Hd of a cam ||5 while the other leg Il@ is arranged for cooperation with a projection lll provided on an overload tripping lever |20 pivoted at |2|. The stops 9D and 9| for the floating lever |52 are formed integrally with this tripping lever. Normally the tripping lever |20 is restrained in the position shown in Figs. l and 2 by means of a current responsive bimetallic thermal element |24, the opposite end |25 of which is rigidly secured to an insulating member |21 pivoted at |28. The insulating member |21 also rigidly secures one end |29 of an ambient temperature responsive bimetallic element |30 the opposite end |31 of which is provided withd an opening through which extends an adjusting screw |36,

the adjusting screw extending through the end 16 of the box I2.

Associated with the tripping lever |20 is a plunger or releasing member |36, one end |31 of which extends through an opening provided in an angular portion |38 of the tripping lever |20, the opening being located to one side of the pivot pin |2|. As shown in Figs. 1l-13, inclusive, the opposite end of the plunger is provided with a rounded end |40 arranged in nesting relation with an angular notch |42 provided in the lower portion |44 of the cam H5. A normally compressed spring encircling the plunger |35 biases the plunger for movement towards the cam ||5 by reason of the engagement of one end of the spring with the inner side of the angular portion |38 of the tripping lever |20 and the engagement of the opposite end of the spring with a shoulder |52 formed integrally with the plunger |35. As shown in Figs. 2 and 11 the longitudinal movement of the plunger is prevented by a latching means comprising a three surface cam |55 carried by the plunger, one surface |55@ of the cam bearing against a surface |50a oi a second three surface cam |50 formed integrally with the tripping lever |20. When the cams are engaged, only a small component of the force of the spring is eiective to bias the tripping lever |20 against the thermal element |20. As shown in Figs. 10 and 1l, the three surface plunger cam |55 and the overload cam |50 are designed so that their adjoining surfaces |55a and |5951. are at such an angle with respect to the direction of movement of the plunger that only the small component of force from the spring |50 acts on the cam |59 in a direction to rotate the tripping member |20 in a counter-clockwise direction about its pivot |2|. It is this small component of the force of the spring which is resisted by the bimetal element |20. It should be here observed that movement of the plunger cam |55 in a clockwise direction, as viewed in Fig. l1, is prevented by the engagement of its end |00 with the notch |02 provided in the lower surface of the cam ||5.

In order to open manualy the circuit controlling device it is only necessary to pull on a button |10 to operate it in a longitudinal direction from the position shown in Figs. l and 2 to the position shown in Fig. 3. It will be observed that the button |10 is secured to an extension |12 formed integrally with the cam H5. As the button |10 is moved longitudinally the cam ||5 is moved from the position shown in Fig. 11 to the position shown in Fig. 12, one side |10 of rounded plunger |00 being engaged by the inclined surface |11 of the angular notch |42 to cause rotation of the plunger |36 in a counter-clockwise direction as viewed in Fig. 11. In Fig. 12 the plunger |36 has been rotated an amount just insuiiicient to move the plunger cam |55 out of engagement with the overload cam |59, a' corresponding enlarged View of the cam being shown in Fig. 10b. As soon as the button |10 is moved a slight additional distance the plunger cam |55 frees itself from the overload cam |59 so that the spring |50 is free to move the plunger |36 towards the button |10.

. Fig. 3, the open circuit positions of the three surface cams |55 and |59 being shown in Fig. 10c.

In order to reclose thedevice |0, the button |10 is pushed longitudinally from the position shown in Fig. 3 to the position shown in Figs. l and 2, the plunger |36 being moved with the button |10 by reason of the engagement of the plunger end |40 with the notch |02. The cam H5 is moved out of engagement with the extension ||3 of the contact operating member 28 permitting the reclosure of the contacts by the over-center spring 35. As the plunger cam |55 is moved into engagement with the overload cam |50, as shown in Fig. 10d, the angle between the engaging surfaces |555 and |5021 is such that the overload cam' |50 is moved out of the path of the plunger cam 55. As soon as the plunger cam clears the overload cam, the spring |50, which has been compressed by the movement of the plunger, causes the tripping lever |20 to return the cam |50 to its latching position shown in Fig. 10a.

With the parts in the position shown in Figs. l and 2 it will be assumed that an overload occurs on the motor operating the cooling apparatus of the refrigerator. That part of the motor circuit through the circuit controlling device i0 may be traced from the terminal 23 by the conductor i 9, conducting screw i0, conductor |1, stationary contact l0, movable contact I6, bronze conductor 25, contact operating member 28, flexible conductor |0| (Fig. 2), heating coil |02 secured in spaced relation with the bimetal thermal element |20, and by conductor |85 to conductor 20 (Fig. l) which as stated above leads to the other terminal connection.

The heat developed by the ow of the overload current through the heating coil |82 causes the thermal element |20 to iiex and move its end |23 out of engagement with the end |20a (Fig. 2) of the tripping lever |20, thereby permitting the tripping lever |20 to rotate in a counter-clockwise direction about its pivot |2| This rotation, as I have stated, is due to the component of force from the spring |50 applied to the tripping lever through the plunger cam |55 and the overload cam |50. As shown in Fig. 10e, the overload cam |59 is moved in the direction of the arrow out of engagement with the plunger cam |55. As soon as the cams disengage, the spring |50 applies its full force on the tripping member |20 to accelerate its movement in the counterolockwise direction.

At the same time the plunger |30 is also freed to move longitudinally to operate the cam l5 and the button |10 to the position shown in Fig. 3, and thereby reset the tripping member |20. Thus as the button |10 moves outwardly from the position shown in Fig. 4, the leg H3 of the contact operating member 20 is engaged by the surface ||ft of the cam ||5 to hold the contacts in the open circuit position. The inclined surface |90 of the cam ||5 then moves against one end |92 of the tripping member |20, causing the tripping member |20 to be returned to its original position shown in Fig. 3. As soon as the thermal lower ambient temperature.

element |20 cools it returns to its original latching position.

If automatic resetting were not provided for, the outer end |23 of the bimetal element |26 would strike against the projection |20a and, of course, in moving the projection |20a back to its original position, the bimetal element would be exed, possibly enough to change the calibration. However, by immediately resetting the tripping member |20, the thermal element is free to return to its original position.

In case the button |70 is held in the closed circuit position shown in Fig. 1 at the time the overload occurs, thethermal element |20 will free the overload tripping member |20, as before, and it will rotate in a counterclockwise direction until its projection lll strikesthe end of the leg M of the contact operating member 23. The force of the spring |50 is suicient to move the contact operating member 28 to the open circuit position irrespective of the button |70 or the position of the over-center spring 35. It will, therefore, be seen that the circuit controlling device |0 is trip-free, i. e., it can not be maintained in the closed position by the operating handle upon the occurrence of an overload. The final positions of the parts with the button |'l0 held in the closed circuit position are shown in Fig. 4.

It will be -apparent from the operations already described that the spring |50 performs a plurality of functions. It biases the tripping member |20 in a direction to open thecontacts; it biases the plunger for longitudinal movement to the open circuit position, and it also serves to reset automatically the tripping member |20 after the overload operation of the circuit controlling device has occurred.

In case the button |70 should be moved from its open circuit position to the closed circuit position before the thermal element |20 has cooled sufficiently to hold the tripping member |20 in its normal position, it will be seen that the tripping member |20 will rotate in a counter-clockwise direction, thereby moving the overload cam |59 .from alinement with the plunger cam |55. The closing of the circuit controlling device depends upon these cams being locked together and, of course, thisis impossible until the tripping member |20 is locked into its normal position shown in Fig. l by the bimetal thermal element |20.

The thermal element |30 responsive to the ambient temperature serves to adjust the overload operation of the device so that the current required for tripping remains constant. 'I'hus as the ambient temperature rises, the element |30 lexes or bends in a direction to rotate the insulating member |27 and the overload thermal element |20 in a clockwise direction as viewed in the drawings to compensate for the flexure of the element |24 due to the increased ambient temperature. Since the movement required of the is therefore the same under the increased ambient temperature the device operates to open the `circuit on the same value of current as for a The motor is thus operated at its full capacity irrespective of .ambient temperature conditions.

It will be observed that the shank |12 of the cam H is slidably mounted within a control knob |80. Normally the knob |80 occupies the position shown in Figs. 1 and 2. However, by rotating the knob |80 in one direction or the other, the control device l0 will function so as to cause'the temperature of the refrigerator to element to release the overload member |20 V rise above the normal average temperature for defrostingv the refrigerator, or to fall below the normal average temperature for quick freezing. As is Well understood by those skilled in the art, after the refrigerator operates for a period of time, frost accumulates on the evaporator. By means of the present invention, the frost can be removed by simply permitting the refrigerator temperature to rise above the melting temperature of the frost. This upper limit is arbitrarily selected and it may be assumed to be 50 F. Provision is made so that the temperature does not vary more than a few degrees from this temperature. The time during which the defrosting occurs is that period during which the temperature of the evaporator is above 32 F. In accordance with my invention, as soon as' a temperature of approximately 50 degrees is reached, the refrigerator automatically resumes its normal operating cycle under the control of the device l0.

In order to initiate the defrosting cycle of operation the knob |80 is rotated in a counterclockwise direction, as viewed in Figs. l and 2, the result of which is the application of additional spring pressure on the operating lever 30 in a direction opposing the expansion of the bellows 50. Since the pressure exerted by the bellows increases with a rising temperature this additional pressure will be overcome as soon as a corresponding higher temperature is attained in the refrigerator. The bellows 50 then oper-- ates the circuit controlling device to the closed circuit position. This additional spring pressure is obtained by means ofa torsion coil spring 200 (Fig. 2) supported on a post 202, one end 200 of the spring bearing against a defrosting lever 200 pivotally supported on the post 202. The opposite end 200 of the spring 200 rests against a threaded collar 209 mounted on an adjusting screw 2 i5, extending through and supported by the spring seat l2. The spring 200 normally biases the defrosting lever 2 05 for rotation in a clockwise direction, as viewed in Figs. 1 and 2. One end 2|6 of the defrosting lever 206 bears against a defrosting cam 2I8 which cam is provided with a square opening 2|79 (Fig. 13) into which extends the square projection 220 formed integrally with the knob |80. the knob |80 is turned toward the defrosting position, a recess 22| formed in the cam is brought into registering relation with the extension 2I|5 so that a predetermined clockwise rotation is permitted for the defrosting lever 206. This clockwise rotation moves an eXtension 225 of the defrosting lever 206 into registering relation with a roller 230 supported on an arm 23| formed integrally with the switch operating lever 30.

The positions of the parts for the defrosting operation are shown in Fig. 6. As the temperature of the refrigerator rises `tothe predetermined high temperature, the pressure of the bellows 50' rotates the operating lever 30 in a counter-clockwise direction, this movement being opposed by temperature control spring 68, and the defrosting spring 200, The roller 230 after engagement with the extension 225 of the defrosting lever 206 rotates the defrosting lever 206 in a counter-clockwise direction until the end 2|@ is removed from the recess 22| in the devfrosting cam.` As soon as the extension 2|S clears the recess, the centering spring 235 (Figs. 2.a.nd 13) quickly returns the knob |80 to its original position shown in Figs. 1 and 2. The

centering spring 235, as shown in Fig. 2, is coiled around the knob |80 with its ends 235e and 235i) located on opposite sides of a stop 235 formed integrally with the front end wall 16 of the casing l2, and a projection 23'1 formed integrally with the cam 2l8. Thus when the knob is rotated in either direction the energy normally stored in the spring 235 is increased. Due to the shape of the recess 22d, however, the coil spring 235 cannot apply suiiicient'force to the extension Zit to move it from the recess. lf the knob HBO, however, is forcibly rotated from the defrosting position to the normal position, the increased force applied through the cam to the extension 2l@ is sucient to move it back to its original position.

Since the temperature control spring 58 is adjustable, it will be seen that the defrosting temperature will vary unless the force of the spring 255 is varied inversely with the change in` spring pressure exerted by the spring 58. The necessary compensation is obtained by the movement of the end 258 of the torsion spring 2U@ with the spring seat i2 provided for the temperature control spring 58. Thus as the temperature control knob 52 is rotated in a counter-clockwise direction thespring seat l2 moves to increase the spring pressure against the operating lever 35. The movement of both the screw 2i5 and the collar 259 with the spring seat rotates the end 255 of the torsion spring 255 in a counterclockwise direction, as viewed in Figs. l and 2, to decrease the pressure exerted by the spring 255 on the deirosting lever 255 a corresponding amount.

ln case it is desired to reduce quickly the refrigerating temperature to a predetermined low or quick freezing temperature, for example, 6 degrees Fahrenheit, the knob l5@ is rotated in a clockwise direction against the bias of the centering spring 235. A quick freeze cam 25@ secured to the deirosting cam 252 is rotated until a recess 250 is moved into registering relation with one end 253 of a quick freeze lever 255 pivotally mounted on the post 252. A quick freeze torsion coil spring 258 encircles the post 222, one end 255 of which bears against the quick freeze lever 25S while the other end 26@ is held against rotation by a threaded collar 256. This collar is mounted on an adjusting screw 25W which is secured to the spring seat l2 by means of a lock nut 2li?. The force from the torsion spring rotates the quick freeze lever in a counterclockwise direction, as viewed in Fig. 2. until the end 253 moves into the recess 25! while the opposite end 272 of the quick freeze lever is rotated to a position adjacent the roller 235, as shown in detail in Fig. 8.

Since the quick freeze spring 25B now acts in opposition to the temperature control spring 58 the pressure in the bellows must be reduced a correspondingly greater amount in order to move the contact l5 to its open circuit position. As soon as this predetermined low pressure is attained, corresponding to the assumed Value'of 6 F., the spring 58 moves the roller 23B carried by the operating lever 3ft against the end 2l2 of the quick freeze lever 25B with suicient force to rotate it in a clockwise direction. As soon as the end'253 of this `lever clears the recess 25H, the centering spring 235 returns the knob |180 to its normal position. The refrigerator then resumes its normal operating cycle.

Ii normal operation of the refrigerator is desired after either the defrosting or quick freezing operations have been initiated, it is only necessary to return forcibly the knob E80 to its normal position shown in Figs. 1 and 2. This return motion is permitted since the knob l is maintained in the quick freeze and the defrost positions by the frictional engagement of the cams 248 and 250 by the corresponding levers 255 and 255.

'During the normal operating cycle the movable contact l5 remains in either its open or closed circuit position for a substantial time in-v For example, with a low ambient tem-- terval. perature the movable contact l5 may remain in the open circuit position for twenty minutes or more. Therefore, the end 272 of the quick freeze lever is arranged to be operated by the quick freeze cam 255 against the roller 235 so as to move the operating lever 3G to the closed circuit position in the event that the quick freeze setting is made when the lever 35 is in open circuit position. The quick freezing operation is accordingly initiated immediately. Since the knob i563 and the cam 255 close the contacts by moving the operating member 55, the overload tripping member l2@ is effective at all times to open the circuit in response to an overload.

In accordance with a further aspect of my invention, l provide a vacation setting for the control device i@ whereby a higher average temperature is maintained in the refrigerator. Accordingly, beverages and the like can be maintained cool with a substantial saving in the cost of operation over the cost of operation for the normal cycle.

The vacation setting is obtained by rotating the temperature control knob 22 in a counterclockwise direction to its minimum temperature position. A cam 255 (Eg. 2) provided with a notch 25H is rotated with the screw ld. .knob 52 reaches its temperature position the notch 2.5i is moved into registering relation with an extension 252 provided on a iol-shaped lever pivoted at B5 and provided with a portion 295 normally arranged in spaced relation with the operating lever 5d. As soon as the recess 29i is in registering relation with the extension 292, the portion 255 is operated into engagement with the operating lever 5G by means of a compression spring 255 mounted at one end on a spring seat 25? formed integrally with the member 255 and mounted at its opposite end on a spring seat 258 carried by a screw 299. The effect of adding the force of the spring 256 to the operating lever 3d is to require a correspondingly higher temperature in the refrigerator to produce sufficient pressure by the bellows 5@ to operate the lever Sil to close the contacts.

While have shown a particular embodiment of my invention, it will be understood, of course, that l' do not wish to be limited thereto since many modiiications may be made, and therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A circuit controlling device comprising circuit control means, operating means for operating said circuit control means to open and close the circuit, a tripping member, means mounting said tripping member for movement from a normal to a tripped position to operate said control means to open the circuit independently of said operating means, a releasing member, latching means forming a connection between said releasing member and said tripping member, a spring,

AS the.

means mounting said spring so as to apply a bias to both of said members, overload means normally restraining one of said members against said bias, and said latching means restraining said other member, said overload means being operable upon overload to release said one member for movement to release said connection between said members whereupon said tripping member operates said control means to open the circuit.

2. A circuit controlling device comprising contacts at least one of which is operable between open and closed circuit positions, a tripping member, pivot means mounting said member for rotation between predetermined positions for causing said contact to move to said open circuit position, a releasing member, a spring located between said releasingmember 'and' said tripping member for applying a force to both of said'members, a surface on o ne of said members inclined with respect to the line of action of said spring, a second surface on the other of said members urged by said spring into engagement with said first. surface, said spring through said surfaces applying only a fraction of its force to move said tripping member and thereby operate said contacts to said open circuit position, overload responsive means normally restraining said tripping member but'operable on overload to free the same, whereupon said tripping member rotates to disengage said surfaces, and said spring then applies its maximum force on said tripping member to operate said contact to said open cire cuit position.

3. A circuit controlling device 'comprising a pair of contacts, means for moving one of said contacts relatively to the other between open and closed circuit positions, a tripping member, means mounting said tripping member for move; ment from a normal to a tripped position to operate said contacts to said open circuit position, a releasing member, a spring for applying a bias to move both of said members, latching means between said tripping member and said releasing member for reducing the bias on said members and for restraining said tripping member in said normal position, and an overload means for causing release of said latching means.

4. A circuit controlling device comprising a circuit control means operable to open and close a circuit, a tripping member, a releasing member, spring means for applying a force to bias said members in predetermined directions with respect to each other, said members being provided with bearing surfaces normally in engagement with each other, said bearing surfaces being inclined with respect to the force applied by said spring means whereby a relatively small com ponent of said force is applied to move said members, means for restraining said releasing member against said component of force, overload responsive means normally restraining said tripping member but freeing said tripping member upon the occurrence of a predetermined overload whereupon the full amount of said force is applied to said tripping member to operate said control means to open the circuit, and a stop for said releasing member.

5. A circuit controlling device comprising control means for opening and closing the circuit, a tripping member operable from a normal position to an overload position to operate said control y means to open said circuit, a second member operable between a normal position and a second position, aspring for applying a force to both of said members, an overload device for restraining one of said members in said normal position against the bias of said spring and operable in response to an overload to free said tripping member for operation to said overload position,

a connection between said one member and the other member for restraining said other member in said normal position, and means cooperatively related with both of said members and operable by said spring after said trippingmember moves.to said overload position to return one of said members to its normal position.

6. A circuit controlling device comprising a tripping member operable from a normal position to an overload position, a second member operable between a normal position and a second position, a spring one end of which acts on said tripping member and the other end of which acts on said second member for biasing said members from said normal positions to said overload and said second positions, restraining means for restraining one of said members in said normal position, a latching means operable by said one member for restraining said other member in said normal position, and means cooperatively related with both of said members for returning one of said members to its normal position after both of said members have been Aoperated respectively to said overload and said second positions.

7. A circuit controlling device comprising a pair of contacts one of which is operable with respect to the other between open and closed circuit positions, a tripping member operable from v a normal postion to anoverload position for operating said contacts to said open circuit position, a second member operable between a normal position and a second position, a spring normally applying a force biasing both ofsaid members.

from said normal positions, restraining means for holding one of said members in its normal position, latching means for holding said other member in its normal position and operable by movement of said one member from said normal position for releasing said other member, and a member having an inclined surface operable by movement of one of said members for returning the other of said members to its normal position.

8. A circuit controlling device comprising a pair of contacts one of which is operable with respect to the other between open and closed circuit positions, a tripping member for causing the operation of said contactsV to said open circuit position, a plunger, cooperating inclined surfaces formed on said plunger and said member, a spring normally acting to move said tripping member, overload means restraining said tripping member against movement by said spring but operable on overload to free said tripping member for operation by said spring, said in- A clined surfaces providing for relative movement between said .plunger and said tripping member and for a reduction in the opening force of said spring when said surfaces are in engagement.

9. A circuit controlling device comprising a contact member operable between -open and closed circuit positions with a snap action, an overload tripping member, a thermal responsive element normally maintaining said tripping member in a iirst position, a spring for biasing said tripping member for movement from said first position to a second position to operate said switch member from said closed position to said open position, a plunger arranged to be acted upon by said tripping spring, latching means between said plunger and said tripping member arranged to be freed by predetermined movement of' said tripping member for applying the force of said spring on said plunger to operate said plunger from one position to another, said plunger being provided with means for returning said tripping member to said rst position and for maintaining said switch member in said open circuit position, said latching means being adapted to be reset by operation of said plunger to said one position.

10. A circuit controlling device provided with a switch member operable between open and closed circuit positions, an operating member for said switch member, overload responsive means' for operating said switch member from its closed to its open circuit position upon the occurrence of a predetermined overload current, comprising a tripping member, a tripping spring normally biasing said tripping member into engagement with said switch member, a thermal responsive device for freeing said tripping member for operation by said tripping spring, a cam operable by said spring into engagement with said switch member, and means operab-le by said spring for returning said tripping member to its rst position as said cam is operated into engagement with said switch member.

11. A circuit controlling device comprising a switch member operable between open and closed circuit positions, an overload tripping member,

means pivoting said tripping member .for rotation.

into engagement with. said switch member, a spring for biasing said tripping member for said rotation, a plunger having one end supporting said spring and the opposite end provided with a projection, a cam provided with a recess for receiving said projection, a three surface cam mounted on said tripping member, a second three surface cam mounted on said plunger, one face of said second cam being arranged to engage one surface of said rst cam to lock said plunger in position with said spring under compression, said extension and said angular recess permitting rotation of said plunger in a direction to release said cams one from the other and to permit the opening of said circuit controlling device.

12. A circuit controlling device comprising a switch member operable between open and closed circuit positions, an operating member for said switch member, a tripping member operable from a rst position to a second position for operating said switch member from said closed circuit position to said open circuit position irrespective of the position of said operating member, a spring for biasing said tripping member for movement from its rst to its second position, and a cam provided with one surface operable into engagement with said switch member to maintain the same in said open circuit position and a second surface operable into engagement with said tripping member to return the same to said rst position after its operation tosaid second position, said spring biasing said cam for operation against said switch member and to return said tripping member to said rst position.

13. A circuit controlling device comprising a switch member operable between open and closed circuit positions, an operating lever, an overcenter spring connected between said operating lever and said switch member for producing a snapl action of said switch member, overload responsive means for operating said switch member from said closed circuit position to said open circuit position irrespective of the position of said operating member comprising a tripping member to move said switch member to said open circuit position against the bias of said over-center spring, a spring connected to said tripping member, a cam provided with two surfaces one of which cooperates with said switch member and the other of which cooperates with said tripping member, connecting means between said spring and said cam operable by predetermined movement of said tripping member to operate said cam into engagement with said tripping member and said switch member to maintain the switch member in said open circuit position and to return said tripping member to said rst position, and a bimetallic thermal element normally maintaining said tripping member in said first position and operable in response to a predetermined ovcrload current to free said tripping member to initiate said overload tripping of said switch member.

14. A circuit controlling device comprising a switch member operable between open and closed circuit positions, an overload tripping member, means mounting said tripping member for rotation into engagement with said switch operating member, a spring for biasing said tripping member for said rotation, a plunger having one end supporting said spring and the opposite end being provided with a pointed projection, a cam provided with a recess for receiving said pointed projection of said plunger, latching means for maintaining said plunger in a predetermined position comprising a three surface cam mountcd'on said tripping member and a second three surface cam mounted on said plunger, one face of said second cam being arranged to engage said face of said rst cam to lock said plunger in position with said spring under compression, a thermal element normally maintaining said overload tripping member out of engagement with said switch operating member and operable in response to a predetermined overload current to free said tripping member for rotation by said spring to release said latching means. said spring first rotating said tripping member into engagement with said switch means and thereafter operating said plunger and said cam longitudinally, and means responsive to said longitudinal move- -ment for returning said tripping member out of engagement with said switch member and for maintaining said switch member in said open circuit position until said cam is moved to reengage said three surface cams.

15, A circuit controling device comprising a pair of contacts, operating means for moving one of said contacts relatively to the other between open and closed circuit positions, a restraining member operable between a normal position and a second position, a spring normally biasing said restraining member to said second position, latching means including a pair of inclined engaging cam surfaces for holding said restraining member in its normal position, manual means for operating said restraining member to force relative sliding movement between said cam surfaces and thereby cause the release of said-latching means, and means eectve upon movement of said restraining member for applying the force of said spring to operate and to maintain said contacts in said open circuit position independently of said operating means.

16. A circuit controlling device comprising a switch member operable between open and closed circuit positions, a tripping member operable from a normal position to an overload position operable from a first position to a second positionfor operating said switch member to its open circuit position, a manual operating member, a plunger having one endslidably mounted in said tripping member and its opposite end supported by said manual operating member, a

spring arranged between said plunger and said.

i said plunger against movement by said spring,

said latching means being releasable by movement l of said tripping member or by movement of said plunger by said manual operating means, said switch member being operatively associated with both saidplunger and said tripping member so as to be operated to its open circuit position by movement of either of said members.

17. A circuit controlling device comprising a switch member operable between open and closed circuit positions, an operating member therefor, temperature responsive means for moving said operating member between predetermined positions, an adjustable spring normally opposing the movement of said operating member by said temperature responsive means, and means for varying at any time by a predetermined amount the bias of said adjustable spring comprising a second spring, and a member biased by said second spring into the path of movement of said operating member, the opposite end of said second spring being connected to said adjustable spring so as to vary inversely the tension in said second spring with respect to the variation in tension of said adjustable spring and means normally maintaining said member out of said path of movement against the bias of said second spring, said last-mentioned means being operable to release said member for movement by said second spring into said path of movement.

18. A circuit controlling device comprising a switch member operable between open and closed circuit positions, an operating member therefor, temperature responsive means for moving said operating member between predetermined positions, an adjustable spring normally opposing the movement of said operating member by said temperatureresponsive means,- and means for varying at any time by a predetermined amount the bias of said adjustable spring comprising a torsion spring, a member having one-portion coni nected to said torsion spring, and operable into the path of movement of said operating member, the opposite end of said torsion spring'being connected to said adjustable spring so as to vary inversely the tension in said torsion spring with respect to the variation in tension of said adjustable spring, a knob operable from a normal position to a second position for controlling said member, and a frictional connection between said knob and said member for maintaining said member into or out of said path vof movement of said operating member, said knob being operable at will between said positions.

19. A circuit controlling device comprising a switchmember operable between open and closed circuit positions, an operating' member therefor, a 'temperature responsive means connected to said operating member for operating the same in response to predetermined temperature variation, a biasing means normally opposing saidv into and out of the path of said operating member, a spring for biasing said pivoted member in a direction to oppose the movement of said operating member, a cam operable from a first position to a second position for moving said end of said pivoted member into the path of said operating lever, and a spring for biasing said cam to said rst position, the connection between said cam and said pivoted member forming a latch between the other endl of said pivoted member and said cam to hold said cam in said second position until said operating member operates said pivoted member to release said cam for rotation in accordance with its bias to its original position. l

20. A circuit controlling device comprising a switch member operable between open and closed circuit positions, an operating member therefor, a temperature responsive means connected to said operating member for operating the same in response to predetermined temperature variation, a biasing means normally opposing said temperature responsive means, a member mounted for pivotal movement about an intermediate point to bring one end of saidv member into and out of the path of said operating member, aspring for biasing said pivoted member in 'a direction to oppose the movement of said operating member, a cam operable from a rst position to a second position for moving said end of said pivoted member into the path of said operating lever,` and av spring for biasing said cam to said rst position, the connection between said cam and said pivoted member forming a latch between the other end of said pivoted member and said cam to hold said camV in said second position until said operating member operates said pivoted member to release said cam for rotation in accordance with its bias toits original position, said latch also being releasable by manual operation o'f said cam from said second position to said iirst position.

21. A circuit controlling device comprising a switch, an operating member movable between open and closed vcircuit positions, means for operating said switch operating member between said positions, avpair of members each provided with biasing means, cam means movable in one` direction to operate one of said members in a direction to oppose movement of said operating member, said cam means also being movable in the opposite direction to operate said other member to oppose movement of said switch operating member, a centering spring for said cam means iorbiasing the same to its original position, each of said members forming latching means for maintaining said cam means in one or the other of its operated positions until after said switch operating member `operates one or the other of said members to release said latching connection Afor modifying the action of said control member as eiiected by said condition responsive means comprising a pair of elements, one manually movable to a position tending to resist movement of said control `member to one of said positions and the other element manually movable to a position tending to resist movement of said control member to the other of said positions, said manually movable elements each positively moving said control member to the desired position if the con trol member is, at the time of operation of the element, in the undesired position.

23. In a control device, a control member movable to two opposite positions, condition responsive means tending to move said control member at times to one of said positions and at other times to the other of said positions, means for modifying the action of said control member as affected by said condition responsive means comprising a pair of elements, manually movable means to position one o said elements in position tending to resist movement or" said control member to one of said positions and the other element tending to resist movement of said control member to the other of said positions, said elements each positively moving said control member to the desired position if the control member is, at the time of operation of the element, ln the undesired position, a pair of arms biased toward each. other, and a stop between Said arms to determine a central position of said manually movable means, said manually movable means having a projection between said arms and adapted to move one of them away from the stop when the manually movable means is moved in one direction and the other away from the stop when it is moved in the opposite direction.

ERNEST ZURCHER. 

